A study from Tanzania reveals that diet has a significant impact on the immune system.
A dietary shift of just two weeks from a traditional African diet to a Western-style diet has been shown to trigger inflammation, weaken the immune response to pathogens, and activate biological pathways linked to chronic lifestyle diseases. In contrast, a traditional African diet, rich in vegetables, dietary fiber, and fermented foods, has demonstrated beneficial effects on both immunity and metabolism. These findings, published in Nature Medicine, underscore the powerful influence of diet on immune function and overall metabolic health.
Across Africa, lifestyle-related diseases such as cardiovascular conditions, diabetes, and chronic inflammatory disorders are on the rise, placing increasing strain on already burdened healthcare systems. Economic growth, urbanization, and greater access to processed foods have contributed to the rapid adoption of Western dietary habits across the continent. To investigate the health impacts of this nutritional transition, researchers from Radboud University Medical Center in the Netherlands and KCMC University in Tanzania conducted a study examining the biological consequences of these dietary changes.
Lifestyle diseases
Seventy-seven healthy men from Tanzania, both urban and rural residents, participated in the study. Some participants who traditionally ate an African diet switched to a Western diet for two weeks, while others who ate a Western diet adopted a traditional African diet. A third group consumed a fermented banana drink daily. As a control, ten participants maintained their usual diet. The researchers comprehensively analyzed the function of the immune system, blood inflammation markers, and metabolic processes at baseline, after the two-week intervention, and again four weeks later.
Participants who switched to a Western diet exhibited an increase in inflammatory proteins in their blood, alongside activation of biological processes linked to lifestyle diseases. Their immune cells also responded less effectively to pathogens. Meanwhile, those who switched to a traditional African diet or consumed the fermented drink showed a reduction in inflammatory markers. Some of these effects persisted even four weeks later, indicating that short-term dietary changes can have long-lasting effects.
Insights from Africa
This is the first study to comprehensively map the health effects of a traditional African diet. ‘Previous research has focused on other traditional diets, such as the Japanese or Mediterranean diet’, says internist Quirijn de Mast from Radboudumc. ‘However, there is just as much to learn from traditional African diets, especially now, as lifestyles in many African regions are rapidly changing and lifestyle diseases are increasing. Africa’s rich diversity in traditional diets offers unique opportunities to gain valuable insights into how food influences health.’
De Mast finds it remarkable how significant the effects of diet are, even after just two weeks. ‘The African diet includes plenty of vegetables, fruits, beans, whole grains, and fermented foods. Our study highlights the benefits of these traditional food products for inflammation and metabolic processes in the body. At the same time, we show how harmful an unhealthy Western diet can be. It typically consists of processed and high-calorie foods, such as French fries and white bread, with excessive salt, refined sugars, and saturated fats. Inflammation is at the root of many chronic conditions, which makes this study highly relevant for Western countries as well.”
Reference: “Immune and metabolic effects of African heritage diets versus Western diets in men: a randomized controlled trial” by Godfrey S. Temba, Tal Pecht, Vesla I. Kullaya, Nadira Vadaq, Mary V. Mosha, Thomas Ulas, Sneha Kanungo, Liesbeth van Emst, Lorenzo Bonaguro, Jonas Schulte-Schrepping, Elias Mafuru, Paolo Lionetti, Musa M. Mhlanga, Andre J. van der Ven, Duccio Cavalieri, Leo A. B. Joosten, Reginald A. Kavishe, Blandina T. Mmbaga, Joachim L. Schultze, Mihai G. Netea and Quirijn de Mast, 3 April 2025, Nature Medicine.
DOI: 10.1038/s41591-025-03602-0
Radboudumc and KCMC University collaborated on this study with international partners from Bonn and Florence. The research was funded by ZonMw/JPI-HDHL.
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